1. Field of the Invention
The present invention relates to a recording and reproducing apparatus, and more particularly to an apparatus arranged to record and reproduce digital image data and additional data.
2. Description of Related Art
In transmitting a large amount of digital data, it is generally practiced to compressively code the digital data so that the transmission can be made at a relatively low transmission rate.
For example, a digital video cassette recorder (VCR) which records and reproduces image data on and from a magnetic tape as digital data is arranged to compress digital image data of a data rate of, say, about 124 Mbps to a data rate of about 25 Mbps which is about one fifth of the original data rate and to record the compressed digital image data on the magnetic tape.
The digital VCR is arranged to compress the amount of information of digital image data by carrying out a DCT (discrete cosine transform) process on the digital image data, quantizing the DCT-processed image data, and variable-length-coding the quantized image data. The step of quantizing the image data is arranged to be variable on the basis of parameters of varied kinds. Further, the data rate is controlled in such a way as to make the amount of codes constant after the process of the variable-length coding.
Among the digital VCRs of this kind, consumer-used digital VCRs arranged to operate on a format prescribed for the HD-Digital VCR Conference have a standard recording-and-reproducing mode (hereinafter referred to as xe2x80x9cSD modexe2x80x9d) and a long-time recording-and-reproducing mode (hereinafter referred to as xe2x80x9cSDL modexe2x80x9d).
In the SDL mode, the number of pixels in the horizontal direction is thinned down to xc2xe of that in the SD mode by adaptively varying the sampling frequency of image data, and the image data is compressively coded at a compressing rate which is 1.5 times as much as the compressing rate of the SD mode. Further, the travel (transport) speed of the tape for recording and reproduction of the SDL mode also differs from that of the SD mode. Therefore, the SD mode and the SDL mode also differ in inclination of recording tracks formed on the magnetic tape.
Therefore, when changing the recording mode from the SD mode over to the SDL mode in recording digital image data on the magnetic tape, a part of a track recorded in the SD mode is apt to be overwritten with a track recorded in the SDL mode at a mode transition part of the recording tape where the change-over of the recording mode takes place.
Further, since the inclination of tracks on the magnetic tape changes at the mode transition part, the conventional digital VCRs are arranged such that, in reproducing a signal from a magnetic tape having the SD mode and the SDL mode commingled, detection of the mode transition takes some length of time. Then, during such mode transition detecting time, an attempt is apt to be made to reproduce in the SD mode a signal recorded in the SDL mode.
As a result, reproduced data comes to include many errors to greatly deteriorate the quality of an image reproduced.
The invention is directed to the solution of the problem of the prior art described above. Therefore, it is an object of the invention to prevent a reproduced image from deteriorating, even when reproducing image data recorded in different recording modes.
To attain the above object, in accordance with an aspect of the invention, there is provided a recording and reproducing apparatus, which comprises recording means for recording, on a recording medium, image data and error information indicative of presence or absence of any error in the image data, reproducing means for reproducing the image data and the error information from the recording medium, interpolating means for interpolating the reproduced image data on the basis of the error information reproduced by the reproducing means, mode change-over means for changing over a recording mode between a first recording mode in which the recording means records the image data and the error information while transporting the recording medium at a first speed and a second recording mode in which the recording means records the image data and the error information while transporting the recording medium at a second speed different from the first speed, and control means for controlling and causing, in response to the change-over of the recording mode effected by the mode change-over means, the recording means to record the error information indicative of the presence of any error together with the image data for a predetermined period of time.
It is another object of the invention to give an adequate reproduced image even at the time of the change-over of the recording mode.
These and further objects and features of the invention will become apparent from the following detailed description of a preferred embodiment thereof taken in connection with the accompanying drawings.